Refined bifunctional deep eutectic solvent for one-step selective indium and tin recovery from spent LCDs.

In this study, a bifunctional deep eutectic solvent (DES), consisting of choline chloride (ChCl) and oxalic acid dihydrate (OAD), is introduced for the efficient and eco-friendly recovery of indium (In) from indium tin oxide (ITO) - coated glass extracted from discarded liquid crystal displays (LCDs). An innovative one - step in - situ separation process is demonstrated, which exhibits high efficiency and selectivity. A comprehensive investigation was conducted into the leaching conditions affecting In recovery, including temperature, duration, solvent ratio, and solid - to - liquid ratio. Response Surface Methodology (RSM) was employed to optimize these parameters, determining the optimal conditions to be an 80 °C treatment for 8 h, a 2.6:1 M ratio of ChCl to OAD, and a solid-to-liquid ratio of 10 g/L. Under these conditions, a remarkable 95.6 % In recovery efficiency was achieved, with tin (Sn) retained as tin oxide (SnO2). Notably, the DES (2.6ChCl:1OAD) maintained a recovery efficiency of approximately 75 % even after six cycles, highlighting its excellent cyclic stability. In addition, a thorough analysis of the reaction pathway and mechanism underlying this separation process is provided. This study not only underscores the superior selectivity and efficiency of DES in In recovery but also establishes its suitability for real - world applications, presenting a novel approach to the valorization of waste LCDs.